title: Variation in the genetic environments of bla(CTX-M-15) in Escherichia coli from the faeces of travellers returning to the United Kingdom.
abstract: OBJECTIVE
  The genetic surroundings of bla(CTX-M-15) in Escherichia coli recovered from faeces of travellers returning to the UK from overseas were compared with those among established UK strains to provide further insights into the spread of bla(CTX-M-15) in the UK.
  
  
  METHODS
  From August 2006 to January 2008, 1031 faecal specimens were collected at the North West London NHS Trust from general practice patients with a clinical history of diarrhoea following recent international travel. Cefuroxime-resistant E. coli were isolated on cystine-lactose-electrolyte deficient agar and those that produced extended-spectrum β-lactamases (ESBLs) were identified by double disc synergy test (DDST). The molecular environments surrounding bla(CTX-M-15) were investigated by PCR, DNA sequencing, gene cloning and northern blotting.
  
  
  RESULTS
  182/1031 (18%) E. coli isolated from returning travellers gave a positive DDST, and were confirmed by PCR to produce CTX-M ESBLs; 174 (96%) had bla(CTX-M-15), including 21 belonging to clone ST131. Among these 174 isolates, the environment upstream of bla(CTX-M-15) consisted of either: (i) an intact ISEcp1 (n = 108); (ii) various lengths of truncated ISEcp1 (n = 58); or (iii) a 24 bp remnant of ISEcp1 (n = 8). Two different promoters were found to transcribe bla(CTX-M-15), resulting in different levels of cephalosporin resistance.
  
  
  CONCLUSIONS
  E. coli with CTX-M-15 ESBL from returning travellers harboured previously seen UK bla(CTX-M-15) genetic environments (intact or 24 bp remnant of ISEcp1) as well as bla(CTX-M-15) genetic environments previously unseen in the UK (various lengths of truncated ISEcp1), which suggest overseas acquisition and highlight the difficulty of control in a time of population mobility and travel.
authors.affiliation: Antibiotic Resistance Monitoring and Reference Laboratory, Health Protection Agency Microbiology Services-Colindale, London, UK. hiran.dhanji@hpa.org.uk
authors.forename: Hiran
authors.initials: H
authors.lastname: Dhanji
authors.forename: Rajesh
authors.initials: R
authors.lastname: Patel
authors.forename: Robert
authors.initials: R
authors.lastname: Wall
authors.forename: Michel
authors.initials: M
authors.lastname: Doumith
authors.forename: Bharat
authors.initials: B
authors.lastname: Patel
authors.forename: Russell
authors.initials: R
authors.lastname: Hope
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015152:Blotting, Northern; D002444:Cefuroxime / Q000494:pharmacology; D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D006801:Humans; D008131:London; D008826:Microbial Sensitivity Tests / Q000379:methods; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014195:Travel; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D004269:DNA, Bacterial; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases; D002444:Cefuroxime